1. Field of the Invention
The invention relates generally to a device and method for auto-calibration of lasers with any number of radiation delivery systems.
2. Invention Disclosure Statement
Laser systems in the medical field are used for a myriad of purposes, utilizing complex and diverse target surfaces, power levels, and dosage levels and rates. In applications of Photodynamic Therapy (PDT), for example, it is critical that actual dosage rates closely match the desired rate for the particular target on the body. In addition, different irradiation systems are used for different treatments. Cylindrical diffusers, bare fibers, and lensed-tip diffusers are just a few of the many diffusion systems that are used in different applications of PDT to ensure effectiveness for the specific treatment sought.
In many applications of PDT and other laser treatments, a system that allows for a single laser source to serve a variety of purposes with different radiation delivery systems for different treatments, including diffusers if needed, is desired. In many cases, one laser source suffices for treatment of a variety of ailments and other related medical problems, provided that different radiation delivery systems or diffusers are available to ensure the effectiveness of each treatment. Therefore, calibration of the output of laser systems with varying radiation delivery systems is critical to the success and safety of the treatment.
Calibration of power levels for different radiation delivery systems or diffusers is difficult, and, at the least, extremely time consuming. In general, the prior art utilizes flat power meters to test lensed tips and bare fiber systems, whereas an integrating sphere is used for calibration of a cylindrical or spherical tip or other types of extended sources such as balloons. It was not considered feasible in the prior art to develop a device capable of calibrating the output of any number of differing diffusers. Diffusers alter the power and/or intensity of a laser source at different levels, making calibration of different laser diffusion systems a difficult task. For example, U.S. Pat. No. 5,798,518 (Coleman et. al) provides a method for calibration of bare fibers by shunting off a certain portion of the laser for calibration and then rejoining the diffusion, based on successful calibration. A safety shutter would open inside the calibration device based on successful testing of the laser. This application of the prior art works only on bare fibers, or perhaps lensed-tip fibers. In any event, there is no ability in the prior art to calibrate dosage or intensity requirements of different radiation delivery systems utilizing one single calibration laser system. Generally, if a single laser system has different delivery systems capable of attaching and emitting from single laser source, a calibration device must be on hand for each system to ensure proper and desired emission of radiation from each system when it is used. This solution is time consuming and costly.
The present invention provides a novel medical laser treatment system with an integrated subsystem capable of calibrating power and dosage levels of the radiation based on the distal end used for each treatment. The source and calibration subsystem are generally an integrated unit, with a mechanism to allow selection or auto-recognition of a wide variety of diffusers to ensure proper calibration of the laser based on the diffuser used. The present invention allows for a single device or system to be used for a wide variety of treatments.